IRS posted thousands of Social Security numbers on website

Members of nonprofit political organizations known as 527s were the victims as the IRS published highly sensitive information to a public database that reports the transactions of these groups.

Public.Resource.org founder Carl Malamud received a phone call and subsequent email from the IRS on June 18 ordering him to delete the information contained in business income tax return forms called 990-Ts, which Malamud received in mid-February. Public.Resource.org reposts publicly available government data in bulk.

Although the data was deleted the following day, the public domain site further investigated the extent of the problem. It determined that there were eight distinct privacy breaches, including the exposure of at least 2,319 Social Security numbers.